The subject matter disclosed herein relates to transient voltage suppression (TVS) devices, and more specifically, to TVS devices implemented as bidirectional diodes having symmetrical breakdown characteristics.
TVS devices are commonly used in electronic devices to protect components from power surges (e.g., transients, over-voltage conditions) in integrated circuits. TVS devices are generally either unidirectional or bidirectional. For an ideal bidirectional TVS device, the breakdown voltages (VB) under positive and negative biases have substantially the same magnitude and, therefore, the breakdown voltage is symmetrical. However, for actual TVS devices, the magnitudes of breakdown voltages under positive and negative biases are often not identical, and the difference between these two values is referred to as the delta VB (ΔVB). In general, a TVS devices with a low ΔVB enables similar protection from over-voltage conditions under both positive and negative voltage polarities.
In general, a bidirectional TVS diode can be a suitable TVS device for protecting electrical nodes whose signals are bidirectional or can have voltage levels both above and below a reference voltage, usually ground. There are different types of bidirectional TVS diodes, among which, punch-through diodes (e.g., Zener or punch-through breakdown) may be desirable for low voltage applications, where the punch-through occurs at a low voltage (e.g., below an avalanche breakdown voltage). However, a conventional bidirectional TVS diode may have shortcomings. In particular, due to various fabrication process limitations, the breakdown voltage of a conventional bidirectional TVS diode may not be symmetrical. As such, a conventional bidirectional TVS diode may not provide the same level of protection from both positive and negative over-voltage conditions.